Patent GB-595806-A (GB)
Title: Improvements in and relating to shock absorbers
IPC: F16F9/34
Filed: 1945-06-20
Abstract: 595,806. Hydraulic shock-absorbers. GABRIEL CO. June 20, 1945, No. 15768. Convention date, Aug. 22, 1944. [Class 108 (iii)] In a fluid shock absorber of the kind in which a piston having two portions 60, 36, Fig. 9, the former being spaced radially inward of the cylinder 22 to leave an annular space 60a with which two passages or groups of passages 61, 35 extending from opposite ends of the piston, communicate, a flexible packing ring 47 being mounted on the first piston portion 60 having a cross section greater than the width, but substantially less than the length, of the space 60a, and movable on a change in direction of piston movement, from a position in which it interrupts communication between the two passages or. groups of passages 61, 35, spring means 49 are provided acting on the packing ring to urge it into the interrupting position. The passages 61 comprise axial circumferential grooves on the piston portion 60, and the passages 35 comprise wedge shaped axial circumferential grooves on the second piston portion 36 which is hollow and communicates with the grooves 61 through a passage 39 in a wall 38 separating the two piston portions 36, 60, and ports 44. This piston portion 36 is closed by a cup shaped member 53 carrying a pin 54 on which is slidably mounted a valve 55 which co-operates with a seating 40 surrounding the lower end of the passage 39. The valve 55 is urged by a spring 56 into engagement with the seating 40 which has a plurality of grooves 41 cut in its face to allow a predetermined leakage of fluid. A member 58 is pressed by a strong spring 59, Fig. 2, against the inner end of the cup shaped member 53 and has projections 58a which engage recesses in a cylinder closure member (not shown) when the shock absorber is collapsed, in order to enable adjustment of the valve 55 to be effected by rotation of the piston rod 19. The packing ring 47 is carried by a flanged ring 65 and the upper abutment of the spring 49 is effected by a flanged plate 62, a pear-shaped aperture of which engages an annular groove 32 in the piston rod. In fitting the plate 62 to the rod the larger portion of the aperture is passed along the rod until it reaches the groove 32, the plate 62 is then moved sideways so that the smaller portion of the aperture, which is concentric with the piston, engages the groove 32. In a modified construction of the upper piston portion 60, Fig. 2, the grooves 61 are replaced by axial cylindrical passages 43 in the wall of the piston. The upper abutment of the spring comprises a flanged plate 50 held in position by a circlip 46 and has apertures which register with the passages 43 and vent holes to release trapped fluid from the annular space 60a. The lower closure member of the shock absorber cylinder is secured by beading over the end of the cylinder wall which is surrounded by an annular reservoir. On the compression stroke, Fig. 2, fluid pressure forces the ring 47 upwards and fluid flows through the grooves 35 and out of the top of the piston via passages 43, with a limited flow passing through the grooves 41 in the seat of valve 55. On the recoil stroke, Fig. 9, the ring 47 prevents flow through the grooves 35 but the valve 55 opens to permit increased flow through the passage 39.